Lots of excellent photographs by Charles S. Lewallen. Has good identifications of many common or notable Oklahoma insects, including less well-known groups (heteroptera, hymenoptera, diptera). Takes some digging to find images.
Table of contents pages are alphabetical by common name. (Listing by families is not complete.) See the list of alphabetical TOC pages
, which includes beetles, lepidoptera, other insects, and spiders. (There are pages on vertebrates too.) The contents pages just list the common name, but the full Latin name is usually listed with the photo.
Worth browsing through for well-marked species. Go Sooners!